Do i have to pay under Liquidity Damage penalty?

I moved to USA from Canada on H1B visa. My H1B holding company is in Virginia and i am in NJ. My employment agreement says these claus as a part of agreement.
EQUITABLE AND OTHER REMEDIES. Employee agrees that Employer will suffer irreparable harm in the event that Employee breaches any of Employee's obligations under this Agreement, and that it is impossible to measure in money the damages which will accrue to Employer in the event of such a breach or threatened breach. Accordingly, if any action or proceeding is commenced by or on behalf of Employer to enforce any of the provisions contained in this Agreement, Employee hereby waives the claim of defense that Employer has an adequate remedy at law or has not been or is not being irreparably injured by such breach or threatened breach, and Employee agrees to not raise such claim or defense in any such action or proceeding. Employee further agrees that Employer shall be entitled to temporary and permanent injunctive relief to restrain any breaches or further violations of this Agreement, without the posting of any bond, and that this right to injunctive relief shall be in addition to any and all of Employer's other remedies and damages, including, but not limited to, costs and reasonable attorney's fees incurred as a result of said breach or threatened breach.

Under these 2 points, my employer is asking $15000 from me as mentioned in Liquidation Damage because i am leaving them early.
Also, when i signed this agreement, i was in Canada so even though i signed does this agreement holds the value in US courts?

Please advice. It will be very helpful.